1. Field of the Invention
The present invention relates, in general, to an optical modulator module package structure and, more particularly, to an optical modulator module package structure in which an optical modulator device and a drive integrated circuit are flip-chip bonded to a substrate, and an opening is blocked using a piece of glass.
2. Description of the Related Art
Recently, micromachining technology has been developed to produce microoptical parts, such as micromirrors, microlenses, and switches, micro-inertial sensors, micro-biochips, and micro-radio communication devices using a process for fabricating semiconductor devices.
Additionally, a MEMS (microelectromechanical system) field, including the micromachining technology and devices and systems produced using this technology, has come to be considered a fabrication technology and an application field.
The MEMS, which means a microelectromechanical system or device, is applied to an optical field. It is possible to produce optical parts having a size of less than 1 mm using micromachining technology. Thereby, it is possible to realize a microoptical system.
The microoptical system is applied to information communication devices, information displays, and recording devices, due to advantages such as rapid response speed, small loss, and ease of integration and digitization.
For example, the microoptical parts, such as micromirrors, microlenses, and optical fiber fixtures, may be applied to devices for storing and recording information, large-screen displays, optical communication devices, and adaptive optics.
In connection with this, micromirrors have been commercialized, or its commercialization has been studied for application to large-screen displays, optical signal distributors, bar code scanners, and optical signal reducers.
Meanwhile, the demand for large screens is growing day by day. In many meetings or exhibitions, participants or spectators receive strong impressions from drawings, pictures, and moving pictures having brilliant colors. Now that large-screen displays have appeared, many people can simultaneously see large screens in meetings in bright locations so that they can see data from their tables.
In most current large-screen displays (for the most case, projectors), a liquid crystal is used as an optical switch. In comparison with conventional CRT projectors, they are small and low-priced, and their optical systems are simple, thus they are frequently used. However, since light is radiated from a light source through a liquid crystal plate to a screen, they are disadvantageous in that optical loss is high.
Recently, optical efficiency has been improved but intrinsic reduction in efficiency during transmission cannot be avoided. In order to further improve optical efficiency and to obtain a clearer image, a commercial device for displaying a large screen using a micromirror has been developed.
As an example of the micromirror used in the large-screen display, there is a reflective-type deformable lattice optical modulator 10, as shown in FIG. 1. The optical modulator 10 is disclosed in U.S. Pat. No. 5,311,360 by Bloom et al. The modulator 10 comprises a reflective surface part and a plurality of reflective-type deformable ribbons 18 which are suspended over an upper side of a substrate 16 and are spaced apart from each other at regular intervals. An insulating layer 11 is deposited on the silicon substrate 16. Subsequently, a sacrificial silicon dioxide film 12 and a silicon nitride film 14 are deposited.
The nitride film 14 is patterned by the ribbons 18, and the silicon dioxide layer 12 is partially etched so that the ribbons 18 are maintained on an oxide spacer layer 12 by a nitride frame 20.
In order to modulate light having a single wavelength of λo, the modulator is designed so that the thickness of the ribbon 18 and the thickness of the oxide spacer 12 are each λo/4.
The lattice amplitude of the modulator 10, which is defined by the distance (d) between a reflective surface 22 of the ribbon 18 and a reflective surface of the substrate 16, is controlled by applying voltage between the ribbon 18 (the reflective surface 22 of the ribbon 16 acting as a fast electrode) and the substrate 16 (a conductive film 24 on a lower side of the substrate 16 acting as a second electrode).
Meanwhile, in order to commercialize the optical modulator, it is necessary to modularize it, and many characteristics must be considered to achieve modularization.